In order to prevent car theft, automatic owners often use steering wheel locks and shift locks in their cars. Although those locks have stiff structures that cannot be destroyed easily, they are susceptible to sophisticated stealing techniques, and it is a matter of time to unlock them. Therefore, anti-theft means using conventional locks is not effective.
Further, automobile anti-theft devices of electronic types are nowadays often used to prevent theft by detecting a stealing intention in advance. This type of electronic alarm systems are usually powered by car battery and activated by anomalous vibrations of the car body. To operate the system, the detecting sensors connected to the control circuit can detect anomalous motions, such as shocks and car door intrusions, and then the an alarm is activated to produce loud sounds, scaring a thief away. However, since the electronic devices are powered by the car batteries, they are complicated to install and easy to be disconnected (therefore, losing the alarm function). It is a further disadvantage that an electronic alarm and a steering wheel lock are independent devices, and therefore double-protecting a car is expensive. It is another disadvantage that conventional automobile alarms can be easily activated by surround shock waves and would annoy the surrounding residents, which may cause an expectation of “false alarm” and reduce the preventive effect of the alarms.